Ablation cable assemblies and a method of manufacturing the same

ABSTRACT

A cable assembly includes a rigid portion, a flexible central portion, and a radiating portion. The rigid portion is configured to couple to a source of electrosurgical energy and to prevent fluid ingress towards the source of electrosurgical energy. The flexible central portion extends from the rigid portion and includes an inner conductor, a dielectric disposed about the inner conductor, and a conductive braid disposed about the dielectric. The radiating portion extends from the central portion and is configured to deliver electrosurgical energy to tissue.

BACKGROUND

1. Technical Field

The present disclosure relates to surgical instruments and, more specifically, to ablation cable assemblies.

2. Discussion of Related Art

Electromagnetic fields can be used to heat and destroy tumor cells. Treatment may involve inserting ablation probes into tissues where cancerous tumors have been identified. Once the ablation probes are properly positioned, the ablation probes induce electromagnetic fields within the tissue surrounding the ablation probes.

In the treatment of diseases such as cancer, certain types of tumor cells have been found to denature at elevated temperatures that are slightly lower than temperatures normally injurious to healthy cells. Known treatment methods, such as hyperthermia therapy, heat diseased cells to temperatures above 41° C. while maintaining adjacent healthy cells below the temperature at which irreversible cell destruction occurs. These methods involve applying electromagnetic fields to heat or ablate tissue.

Devices utilizing electromagnetic fields have been developed for a variety of uses and applications. Typically, apparatuses for use in ablation procedures include a power generation source, e.g., a microwave generator that functions as an energy source and a surgical instrument (e.g., microwave ablation probe having an antenna assembly) for directing energy to the target tissue. The generator and surgical instrument are typically operatively coupled by a cable assembly having a plurality of conductors for transmitting energy from the generator to the instrument, and for communicating control, feedback, and identification signals between the instrument and the generator.

As electromagnetic fields can be induced at a distance by microwave probes, microwave ablation has the potential to create large active zones whose shapes can be determined and held constant by design. Furthermore, the shape and size can be determined through design to fit a specific medical application. By utilizing a predetermined active zone to create a predictable ablation zone, and not relying upon the indeterminate passive ablation zone, microwave ablation can provide a level of predictability and procedural relevance not possible with other ablative techniques.

The shape of the active zone about an antenna is determined by the frequency of operation, the geometry of the antenna, the materials of the antenna, and the medium surrounding the antenna. Operating an antenna in a medium of dynamically changing electrical properties, such as heating tissue, results in a changing shape of the electromagnetic field, and therefore a changing shape of the active zone. To maintain the shape of the active zone about a microwave antenna, the degree of influence on the electromagnetic field of the surrounding medium's electrical properties are reduced.

The size of the active zone about an antenna is determined by the amount of energy which can be delivered to the antenna. With more energy delivered to the antenna, larger active zones can be generated. To maximize the energy delivered to the antenna, the size of an inner conductor of the cable assembly and a dielectric of the cable assembly about the inner conductor should be maximized and the size of an outer conductor of the cable assembly should be minimized.

SUMMARY

This disclosure relates generally to an ablation cable assembly that includes a water tight semi-rigid proximal portion and a flexible distal portion. The flexible distal portion includes an exposed outer conductor that can be in contact fluids such as dielectric fluids, cooling fluids, or bodily fluids. As detailed below, the thickness of the outer conductor is minimized to allow a larger thickness of a dielectric and an inner conductor for a given diameter of the cable assembly.

In an aspect of the present disclosure, a cable assembly includes a rigid portion, a flexible central portion, and an radiating portion. The rigid portion is configured to couple to a source of electrosurgical energy and to prevent fluid ingress. The flexible central portion extends from the rigid portion and includes an inner conductor, a dielectric disposed about the inner conductor, and a conductive braid disposed about the dielectric. The radiating portion extends from the central portion and is configured to deliver electrosurgical energy to tissue.

In aspects, the conductive braid is pregnable by fluid. The rigid portion and the central portion may be configured to deliver at least 150 watts of continuous electrosurgical energy to the radiating portion. The entire cable assembly may have a diameter in a range of less than about 0.01 inches to about 0.5 inches, 0.02 inches to about 0.4 inches, 0.03 inches to about 0.3 inches, 0.04 inches to about 0.2 inches, 0.05 inches to about 0.1 inches (e.g., about 0.045 inches). The conductive braid may be in tension between the rigid portion and the radiating portion.

In some aspects, the rigid portion includes a rigid tube that is disposed about the dielectric and that is in electrical communication with the conductive braid. The rigid tube may be in intimate contact with the dielectric to prevent fluid ingress towards a proximal portion of the cable assembly. A proximal end of the inner conductor may extend from the rigid tube. A distal portion of the rigid tube may fix the position of a proximal end of the conductive braid relative to the dielectric. The distal portion of the rigid tube may be flared over a proximal end of the conductive braid of the central portion. The flexible portion may include a tube shrunk over a joint defined between the rigid tube and the conductive braid to seal the joint. The tube shrunk over the joint may also provide strain relief for the joint.

In certain aspects, the radiating portion includes a first step and a second step. The first step may be formed from a first dielectric tube and a second dielectric tube and the second step may be formed from the second dielectric tube. The combined thickness of the first and second dielectric tube may be less than the thickness of the dielectric. The second dielectric tube may extend proximally from the second step to overlap the first dielectric tube and the distal end of the dielectric to seal a first step down between the first step and the dielectric. The second dielectric tube may extend distally from a distal end of the conductive braid. The radiating portion may include a distal tip of the inner conductor that extends from a distal end of the second dielectric tube.

In particular aspects, the conductive braid extends over the first step and the second step. The conductive braid may be tucked against the distal end of the dielectric to form a discrete first step down between the dielectric and the first step. The conductive braid may be tucked against a distal end of the first step to form a discrete second step down between the first and second steps.

In aspects, the conductive braid extends over the second step and the radiating portion includes a choke braid that is disposed about the conductive braid distal of the second step down. A proximal portion of the choke braid may be in electrical communication with the conductive braid. The radiating portion may include a dielectric choke tube that is disposed between the choke braid and the conductive braid that is position distal of the proximal end of the choke braid. The radiating portion may include a third tube that is disposed about the conductive braid and the choke braid. A proximal portion of the third tube may be disposed about the first step and a distal portion of the third tube may be disposed about a portion of the choke tube extending distally from a distal end of the choke braid.

In another aspect of the present disclosure, a method of manufacturing a cable assembly includes drawing a rigid tube over a proximal portion of a dielectric of a coaxial cable, trimming a proximal end of the dielectric, exposing a length of an inner conductor at a distal end of the coaxial cable, forming an radiating portion about the exposed length of the inner conductor, and leaving the conductive braid exposed between the rigid tube and the radiating portion such that fluid may impregnate the conductive braid. Forming the radiating portion may tension the conductive braid between the rigid tube and the radiating portion.

In aspects, the method includes verifying a diameter of the dielectric at an end of the coaxial cable before drawing the rigid tube over the proximal portion of the dielectric. The method may include coating a proximal portion of the conductive braid and trimming the proximal end of the conductive braid to leave a coated proximal portion of the conductive braid about the dielectric before drawing the rigid tube over the proximal portion of the dielectric. Drawing the rigid tube over the proximal portion of the dielectric may include positioning the distal end of the rigid tube distally beyond the coated proximal portion of the conductive braid. The method may include flaring the distal portion of the rigid tube before positioning the distal portion of the rigid tube distally beyond the coated proximal portion of the conductive braid.

In some aspects, the method includes measuring a length of the dielectric extending beyond a proximal end of the inner conductor after drawing the rigid tube over the proximal portion of the dielectric to verify a seal is formed between the rigid tube and the dielectric. The method may include sealing a joint between the distal end of the rigid tube and the conductive braid with a shrink tube disposed about the rigid tube and the conductive braid. The method may include reinforcing the proximal portion of the rigid tube before trimming the proximal end of the dielectric. Reinforcing the proximal portion of the rigid tube may include tin tipping the proximal portion of the rigid tube. The method may include sharpening the proximal portion of the inner conductor after trimming the proximal end of the dielectric.

In certain aspects, exposing a length of the inner conductor at the distal portion of the coaxial cable includes laser stripping the dielectric from the inner conductor. Forming the radiating portion about the exposed length of the inner conductor may include shrinking a first dielectric tube over the inner conductor with a proximal end of the first dielectric tube abutting a distal end of the dielectric. Forming the radiating portion may include shrinking a second dielectric tube over the distal end of the dielectric, the first dielectric tube, and a portion of the exposed inner conductor. Wherein forming the radiating portion includes extending the conductive braid over the first and second dielectric tubes, tucking the conductive braid into a joint between the distal end of the dielectric tube and the proximal end of the first dielectric tube to form a first discrete step down and tucking the conductive braid about the distal end of the first dielectric tube to form a second discrete step down.

In particular aspects, forming the radiating portion includes shrinking a choke tube over the conductive braid with a proximal end of the choke tube distally spaced from the second step down. Forming the radiating portion may include positioning a choke braid over the choke tube with a proximal portion of the choke braid extending proximally beyond the proximal end of the choke tube and the distal end of the choke braid proximally spaced from a distal end of the choke tube. Positioning the choke braid over the choke tube may include joining the proximal portion of the choke braid to the conductive braid proximal of the choke tube. Joining the proximal portion of the choke braid to the conductive braid may include soldering the proximal portion of the choke braid to the conductive braid such that the choke braid and the conductive braid are in electrical communication. Forming the radiating portion may include shrinking a third tube over the conductive braid and the choke braid with a proximal end of the third tube positioned about the choke tube distal to the distal end of the choke braid.

In aspects, forming the radiating portion includes trimming a distal end of the conductive braid to expose a portion of the second dielectric tube to form a feedgap of the radiating portion. A distal radiating portion may be connected to the exposed inner conductor beyond a distal end of the second dielectric tube. The distal radiating portion may be soldered to the exposed inner conductor. The distal radiating portion may be abutted to the distal end of the second dielectric tube.

Further, to the extent consistent, any of the aspects described herein may be used in conjunction with any or all of the other aspects described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the present disclosure are described hereinbelow with reference to the drawings, which are incorporated in and constitute a part of this specification, wherein:

FIG. 1 is a side view of an ablation cable assembly 10 provided in accordance with the present disclosure;

FIG. 2 is a side view of coaxial cable forming a portion of the ablation cable assembly 10 of FIG. 1;

FIG. 3 is a cross-sectional view taken along section line 3-3 of FIG. 2;

FIG. 4 is an enlarged view of an end portion of the coaxial cable of FIG. 2;

FIG. 5 is a perspective view of a tool engaged with the end of the coaxial cable of FIG. 4;

FIG. 6 is a side view of the proximal portion of the coaxial cable of FIG. 2 with a braid compressed to expose a dielectric of the coaxial cable;

FIG. 7 is a side view of the proximal portion of coaxial cable of FIG. 6 with the braid pulled over an end of the dielectric;

FIG. 8 is a side view of the coaxial cable of FIG. 7 with an end of the braid plated;

FIG. 9 is a partial perspective view of an end of the coaxial cable of FIG. 8 extending from jaws of a clamping device;

FIG. 10 is a partial perspective view showing the proximal portion of the coaxial cable of FIG. 9 with a portion of the dielectric exposed;

FIG. 11 is a partial perspective view of the end of the coaxial cable of FIG. 10 extending from jaws of a clamping device;

FIG. 12 is a partial perspective view showing the proximal portion of the coaxial cable of FIG. 11 removed from the jaws;

FIG. 13 is a partial side view showing the ends of the coaxial cable of FIG. 12 with a length the dielectric exposed in the connection portion;

FIG. 14 is a partial side view showing a copper tube disposed over the connection portion of FIG. 13;

FIG. 15 is a cross-section taken along section line 15-15 of FIG. 1;

FIG. 16 is a partial side view showing a portion of the copper tube of FIG. 14;

FIG. 17 is a partial side view showing a sleeve disposed over the copper tube of FIG. 14;

FIG. 18 is a partial side view of the distal portion of the coaxial cable of FIG. 2 with the braid compressed to expose the dielectric;

FIG. 19 is a partial side view showing the distal portion of the coaxial cable of FIG. 18 with the dielectric stripped from over a portion of an inner conductor;

FIG. 20 is a partial side view showing the distal portion of the coaxial cable of FIG. 19 with a first tube disposed about the inner conductor;

FIG. 21 is a partial side view of the first tube in an abutting relationship with the dielectric of the coaxial cable of FIG. 20;

FIG. 22 is a partial side view of a second tube disposed over the first tube of FIG. 21;

FIG. 23 is a partial side view of the second tube shrunk over the dielectric, the first tube, and the inner conductor of FIG. 22;

FIG. 24 is a partial side view showing the distal portion of the coaxial cable of FIG. 23 with the braid extended past the distal end of the inner conductor;

FIG. 25 is an enlarged partial view of the coaxial cable of FIG. 24 illustrating the transition between the dielectric and the first step down of a distal radiator portion of the coaxial cable;

FIG. 26 is a cross-sectional view taken along section line 26-26 of FIG. 25 illustrating a first step down;

FIG. 27 is a partial side view of a tin-dipped distal portion of the coaxial cable;

FIG. 28 is a partial perspective view of a gap tool positioned about a second step down of the coaxial cable and a third tube disposed over the braid of the distal portion of the coaxial cable;

FIG. 29 is a partial side view of the choke tube shrunk over the second step down of the distal radiator portion;

FIG. 30 is a partial perspective view of a pin enlarging a diameter of a choke braid;

FIG. 31 is a partial side view of the choke braid disposed over the radiator portion with a first end of the choke braid positioned over the second step down;

FIG. 32 is a partial side view of the radiator portion of the coaxial cable assembled to the choke braid;

FIG. 33 is a cross-sectional view taken along section line 33-33 of FIG. 32;

FIG. 34 is a an enlarged partial view of the radiator portion trimmed from the choke braid to a distal portion of the inner conductor;

FIG. 35 is an enlarged partial view of the distal portion of the radiator portion;

FIG. 36 is a partial perspective view of a connector disposed over the distal end of the inner connector;

FIG. 37 is a partial side view showing the proximal connection portion with a fourth tube shrunk over the copper tube and the braid;

FIG. 38 is an enlarged partial view of a tin-dipped proximal portion of the copper tube of FIG. 37;

FIG. 39 is an enlarged partial view showing the proximal portion of the inner conductor extending from a proximal end of the copper tube of FIG. 38

FIG. 40 is a cross-sectional view taken along section line 40-40 of FIG. 1;

FIG. 41 is a cross-sectional view taken along section line 41-41 of FIG. 1;

FIG. 42 is a cross-sectional view taken along section line 42-42 of FIG. 1;

FIG. 43 is a cross-sectional view taken along section line 43-43 of FIG. 1;

FIG. 44 is a cross-sectional view taken along section line 44-44 of FIG. 1;

FIG. 45 is a cross-sectional view taken along section line 45-45 of FIG. 1;

FIG. 46 is a cross-sectional view taken along section line 46-46 of FIG. 1;

FIG. 47 is a cross-sectional view taken along section line 47-47 of FIG. 1;

FIG. 48 is a cross-sectional view taken along section line 48-48 of FIG. 1;

FIG. 49 is a cross-sectional view taken along section line 49-49 of FIG. 1; and

FIG. 50 is a cross-sectional view taken along section line 50-50 of FIG. 1.

DETAILED DESCRIPTION

This disclosure relates generally to an ablation cable assembly that includes a water tight semi-rigid proximal portion, a flexible central portion, and a radiating portion. The central portion includes an exposed outer conductor that can be in contact and/or impregnated with fluids such as saline, dielectric fluids, cooling fluids, or bodily fluids. The fluids can be pressurized. As detailed below, the thickness of the outer conductor is minimized to maximize a thickness of a dielectric and an inner conductor for a given diameter of the cable assembly. By maximizing the thickness of the dielectric and the inner conductor the power handling of the ablation cable assembly can be increased such that the radiating portion can continuously deliver at least 150 watts of electrosurgical energy to tissue. In addition, by maximizing the thickness of the dielectric and the inner conductor attenuation for the cable assembly can be reduced. Further, exposing the outer conductor to fluids allows for increased cooling of the ablation cable assembly. The ablation cable assembly is formed from a plurality of dielectric tubes that overlap one another at joints between the tubes to prevent fluid from contacting an inner conductor of the ablation cable assembly.

Embodiments of the present disclosure are now described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein, the term “clinician” refers to a doctor, a nurse, or any other care provider and may include support personnel. Throughout this description, the term “proximal” refers to the portion of the device or component thereof that is closest to the clinician and the term “distal” refers to the portion of the device or component thereof that is farthest from the clinician.

With reference to FIG. 1, an exemplary ablation cable assembly 10 is shown in accordance with the present disclosure. The ablation catheter assembly 10 includes a radiating portion 20, a rigid or connection portion 30, and a central portion 40 between the radiating portion 20 and the connection portion 30. The radiating portion 20 is formed to inhibit fluid ingress between a dielectric 130 and an inner conductor 140 (FIG. 3). In addition, the radiating portion 20 precisely positions conductor and dielectric segments, maintains critical dimensional tolerances, and is flexible. The connection portion 30 inhibits fluid ingress about the inner conductor 140 and is rigid or semi-rigid to assist in navigation of the radiating portion 20. The ablation catheter assembly 10 may have an overall diameter of about 2 mm which would be suitable for continuously delivery 150 watts of electrosurgical energy to tissue in connection with a bronchoscopic navigation system (not shown). Experimentation has shown that ablation catheter assemblies of the construction disclosed herein can have a diameter of less than 2 mm and continuously deliver 150 watts of electrosurgical energy to tissue. For an example of a bronchoscopic navigational system and uses thereof reference can be made to U.S. patent application Ser. No. 14/753,229, filed Jun. 29, 2015, the entire contents of which are herein incorporated by reference.

Referring to FIGS. 2-39, the construction and a method of manufacturing the ablation catheter assembly 10 is described in accordance with the present disclosure. Specifically, the construction of the radiating portion 20 and the connection portion 30 from a flexible coaxial cable 100 will be described.

Initially, referring to FIGS. 2 and 3, a flexible coaxial cable 100 is provided having an outer diameter D₁ and a length L₁. The outer diameter D₁ is in a range of about 0.0300 inches to about 0.0500 inches (e.g., about 0.04 inches) and the length L₁ is in a range of about 10 inches to about 60 inches (e.g., about 12 inches). It will be appreciated that if the length of the coaxial cable 100 is greater than a desired length L₁, the coaxial cable 100 may be cut to a desired length L₁.

The coaxial cable 100 is flexible and has an outer conductive braid 120, a dielectric 130 disposed within the braid 120, and an inner conductor 140 disposed within the dielectric 130. The diameter of the inner conductor 140 and the thickness of the dielectric 130 are maximized and the thickness of the conductive outer braid 120 is minimized. The inner conductor 140 is formed of a solid conductive material (e.g., copper, stainless steel, silver, gold, or platinum) and the dielectric 130 is formed from a solid insulative material (e.g., polytetrafluoroethylene (PTFE)). The dielectric 130 may be transparent or translucent. The conductive outer braid 120 is formed from a weave of flat wire stock which reduces the thickness of the conductive outer braid 120 and permits fluids to penetrate or impregnate the conductive outer braid 120. It will be appreciated that by forming the conductive outer braid 120 from flat wire stock reduces the thickness of the conductive outer braid 120 when compared to braids formed from rounded wire stock. The conductive outer braid 120 may also be formed of any conductive material including copper, silver, gold, or platinum, though stainless steel is commonly used.

As shown in FIG. 6, the braid 120 is pushed back at a first end 112 from over the dielectric 130 of the coaxial cable 100 to expose a length L₂ of the dielectric 130. The exposed length L₂ of the dielectric 130 maybe in a range of about 1 inch to about 4 inches (e.g., about 3 inches). The exposed length L₂ of the dielectric 130 is measured to verify that the diameter D₂ of the dielectric 130 is greater than a minimum acceptable diameter. The minimum acceptable diameter of the dielectric 130 is determined by a required power output of the radiating portion 20 (FIG. 1) and materials of the dielectric 130 and the inner conductor 140. It is appreciated that the inner conductor 140 is disposed within the dielectric 130. For example, when the dielectric 130 is made of PTFE, the inner conductor 140 may be a solid copper wire, and the required power output of the ablation catheter assembly 10 may be up to about 150 W, the minimum required diameter of the dielectric 130 is in a range of about 0.017 inches to about 0.490 inches (e.g., about 0.036 inches). The inner conductor may be made from solid copper wire, copper clad steel, silver plated copper clad steel, steel, solid silver wire, or other suitable conductive materials.

A tool (e.g., a micrometer or a die (not shown)) is used to measure the diameter D₂ of the dielectric 130. If the diameter D₂ of the dielectric 130 at the first end 112 of the coaxial cable 100 is less than the minimum required diameter of the dielectric 130, the dielectric 130 at the other or second end 114 of the coaxial cable 100 is checked by pushing back the braid 120 and measuring the diameter D₂ of the dielectric 130 at the second end 114 is performed. If the diameter D₂ of the dielectric 130 of the first and second ends 112, 114 of the coaxial cable 100 are less than the minimum required diameter of the dielectric 130, the coaxial cable 100 is discarded and the preceding steps are repeated until the diameter D₂ of the dielectric 130 of one of the first or second ends 112, 114 of the coaxial cable 100 is greater than or equal to the minimum required diameter of the dielectric 130. Only the dielectric 130 at the first end 112 of the coaxial cable 100 is required to have a diameter D₂ greater than or equal to the minimum required diameter, thus, if the first end 112 has a diameter less than the minimum required diameter and the second end 114 has a diameter equal to or greater than the minimum required diameter the first and second ends 112, 114 of the coaxial cable 100 can be swapped. The first end 112 has an end 142 of the inner conductor 140 and the second end 114 has an end 144 of the inner conductor 140. It will be appreciated that the dielectric 130 at the radiating portion 20 may have a diameter greater or less than the minimum required diameter of the dielectric 130.

Referring now to FIG. 7, in the first step in forming the connection portion 30 the braid 120 drawn over an end 132 of the dielectric 130 a length L₃ and the braid 120 is positioned flush with the end 134 (FIG. 18) of the dielectric 130 at the second end 114 of the coaxial cable 100 (FIG. 2). The length L₃ can be any length as the first end 112 can be trimmed as detailed below; however, it is contemplated that the length L₃ is in a range of about 0.125 inches to about 0.375 inches (e.g., about 0.25 inches).

With reference to FIG. 8, a length L₄ of the connection portion 30 is coated or plated. For example, the length L₄ can be tin-dipped in a solder (e.g., SN96 lead-free solder). The length L₄ is approximately twice the length L₃. Similar to the length L₃, the length L₄ can be any length as the first end 112 can be trimmed as detailed below; however, it is contemplated that the length L₄ is in a range of about 0.25 inches to about 0.75 inches (e.g., about 0.5 inches). Tin dipping of the length L₄ of the connection portion 30 may include inserting the length L₄ of the connection portion 30 into liquefied solder in approximately 1 second and removing the length L₄ of the connection portion 30 from the liquefied solder in approximately 1 second without allowing the length L₄ of the connection portion 30 to dwell within the liquefied solder between the inserting and removing of the length L₄ of the connection portion 30.

Referring to FIG. 9, the coated length L₄ of the connection portion 30 is positioned in a clamp 1030 which holds the connection portion 30 with the coated length L₄ of the connection portion 30 extending from the jaws 1030. A length L₅ (FIG. 8) of the coated length L₄ of the connection portion 30 is positioned within the jaws 1030 with the remainder of the coated length L₄ of the connection portion 30 extending from the jaws 1030. The length L₅ can be in a range of about 0.01 inches to about 2 inches or in a range of about 0.02 inches to about 0.05 inches (e.g., about 0.035 inches). With the length L₅ of the coated length L₄ of the connection portion 30 positioned within the jaws 1030, a cutting tool (e.g., a razor blade (not shown)) is used to trim and remove the portion 122 of the braid 120 extending from the jaws 1030 without cutting the dielectric 130. Trimming the braid 120 leaves the length L₅ of the coated length L₄ of the braid 120 with a first end 132 of the dielectric 130 exposed as shown in FIG. 10. The coated length L₅ of the braid 120 prevents the end of the braid 120 from unraveling or fraying.

With reference to FIG. 11, the connection portion 30 is repositioned within the jaws 1030 such that a length L₆ of the braid 120 is exposed from the jaws 1030. The length L₆ includes the coated length L₅ and is in a range of about 0.04 inches to about 0.07 inches (e.g., about 0.055 inches). With the length L₆ exposed from the jaws 1030, a marking tool (e.g., permanent marker (not shown)) is used to create a mark 125 about the braid 120 to indicate the length L₆ without damaging the braid 120 as shown in FIG. 12.

Referring now to FIG. 13, the connection portion 30 is removed from the jaws 1030 and the braid 120 is retracted to expose a length L₇ of the dielectric 130 at the connection portion 30. This is possible in part because the solder used for the tin dipping process does not permanently adhere to the PTFE of the dielectric 130. The length L₇ is in a range of about 2 inches to about 12 inches (e.g., about 4 inches). As the braid 120 is retracted from over the connection portion 30, the braid 120 is tightened or “milked” from the connection portion 30 towards the radiating portion 20 (FIG. 1) such that the braid 120 is smooth along the length of the coaxial cable 100. When the braid 120 is smooth and the length L₇ of the dielectric 130 is exposed at the connection portion 30, a portion of the braid 120 is trimmed at the radiating portion 20 such that the braid 120 extends beyond the dielectric 130 at the radiating portion 20 (i.e., over the end 144 of the inner conductor 140). The braid 120 can extend beyond the dielectric 130 can be any length; however it is contemplated that this position of the braid 120 has a length of about 0.05 inches to about 10 inches (e.g., about 0.5 inches). The portion 126 of the braid 120 may discarded or saved for creation of a choke braid 340 (FIG. 29) for the radiating portion 20 as detailed below.

With reference to FIG. 14, a rigid tube 210 is provided having an inner diameter which is approximately equal to the diameter D₁ of the coaxial cable 100 (i.e., the outer diameter of the braid 120). The outer diameter of the rigid tube 210 is in a range of about 0.03 inches to about 0.04 inches (e.g., about 0.0319 inches or about 0.0331 inches). The rigid tube 210 is formed of a conductive material or be constructed from a base material and plated with a different and highly conductive material. For example, the rigid tube 210 may be formed entirely from copper or may be constructed from stainless steel and plated with copper, silver, or gold. By using a base material a material having a different stiffness than the plating material may be advantageously utilized.

Initially, an end portion 214 of the rigid tube 210 is flared such that the end portion 214 will fit over the coated length L₅ of the braid 120 to the mark 125. A flaring tool (not shown) may be used to flare the end portion 214 of the rigid tube 210. With the end portion 214 of the rigid tube 210 flared, the rigid tube 210 is slid over the length L₇ of the dielectric 130 such that the flared end portion 214 of the rigid tube 210 is positioned at the mark 125 as shown in FIG. 14 (i.e., the flared end portion 214 is over about half of the mark 125). While sliding the rigid tube 210 over the length L₇ of the dielectric 130, the braid 120 and the dielectric 130 are held beyond the mark 125 to prevent the braid 120 from sliding relative to the dielectric 130 such that the length L₇ remains constant. In addition, the rigid tube 210 may be rotated as it is slid over the length L₇ to assist in the positioning of the end portion 214 of the rigid tube 210 at the mark 125.

When the end portion 214 of the rigid tube 210 is positioned at the mark 125, the rigid tube 210 is drawn down over the braid 120 and the dielectric 130 from the flared end portion 214 of the rigid tube 210 towards a distal end 212 of the rigid tube 210 such that the end portion 214 of the rigid tube 210 secures the coated length L₅ (FIG. 12) of the braid 120 to the dielectric 130. Drawing down the rigid tube 210 over the dielectric 130 compresses and extrudes a portion of the dielectric 130 over the end 142 of the inner conductor 140 as shown in FIG. 16 such that an end 132 of the dielectric 130 extends proximally over the end 142 of the inner conductor 140 a length L₈. The length L₈ has a minimum distance of about 0.020 inches to ensure that the rigid tube 210 is drawn tightly over the dielectric 130 (i.e., is in intimate contact with the dielectric 130) to form a water tight seal between the rigid tube 210 and the dielectric 130. If the length L₈ is less than 0.020 inches the coaxial cable 100 may be discarded. In addition, if the end 142 of the inner conductor 144 does not extend from the end 212 of the rigid tube 210, the coaxial cable 100 is discarded. It will be appreciated that during the drawing of the rigid tube 210, the end 134 of the dielectric 130 remains flush with the end 144 of the inner conductor 140.

Further, after the rigid tube 210 is drawn over the dielectric 130, a sleeve 220 may be slid over the rigid tube 210 to identify the catheter assembly 10 (FIG. 1) as shown in FIG. 17. The sleeve 220 may be preshrunk such that the sleeve 220 fits snugly over the rigid tube 210. The sleeve 220 may be preprinted with identifying indicia (e.g., all or a portion of a serial number or an RFID tag) of the final catheter assembly 10. Alternatively, before or after the rigid tube 210 is drawn down, the rigid tube 210 can be etched or labeled with identifying indicia of the final catheter assembly 10. It will be appreciated that the sleeve 220 may be a temporary identification member that is used to identify the catheter assembly 10 during manufacturing and may be removed during or after the manufacturing process.

Referring now to FIGS. 18-36, with the rigid tube 210 fixing the braid 120 to the dielectric 130, the assembly of the remainder of the catheter assembly 10 including the radiating portion 20 is performed in accordance with the present disclosure. Initially as detailed above, the braid 120 was trimmed to leave the braid 120 extending over the end 134 of the dielectric 130. The braid 120 is now pulled back over the dielectric 130 (i.e., towards the connection portion 30 and the rigid tube 210) to expose a length L₉ of the dielectric 130 as shown in FIG. 18. The length L₉ can be in a range of about 2 inches to about 15 inches or in a range of about 5 inches to about 8 inches (e.g., about 6 inches). The length L₉ of the dielectric 130 is then removed or stripped to expose the inner conductor 140 along the length L₉ as shown in FIG. 19. It is contemplated that any known means of stripping the length L₉ of the dielectric 130 may be used including, but not limited to, laser stripping.

Referring now to FIG. 20, a first shrink tube 310 is slid over the end 144 of the inner conductor 140 until an end 312 of the first shrink tube 310 abuts the dielectric 130. The first shrink tube 310 has a length L₁₀ which can be in a range of about 0.2 inches to about 3 inches or in a range of 0.7 inches to about 0.9 inches (e.g., about 0.8 inches). The first shrink tube 310 forms a “first step 302” of the completed cable assembly 10 (FIG. 1). It will be appreciated that the length L₁₀ may be adjusted such that the total length of the first step 302 of the cable assembly 10 is in a range of about 0.2 inches to about 5 inches or in a range of about 0.8 inches to about 0.86 inches (e.g., about 0.83 inches) as detailed below. With the first shrink tube 310 abutting the dielectric 130, the first shrink tube 310 is shrunk over the inner conductor 140 from the proximal end 312 of the first shrink tube 310 to a distal end 314 of the first shrink tube 310. To ensure that after shrinking the first shrink tube 310 is in abutting relationship with the dielectric 130 (i.e., that there is no gap between the first shrink tube 310 and the dielectric 130), an initial length (e.g., about 0.25 inches) of the first shrink tube 310 may be shrunk and the abutting relationship verified before shrinking the remainder of the first shrink tube 310. If there is a gap between the first shrink tube 310 and the dielectric 130 after the initial length is shrunk, the end 312 of the first shrink tube 310 may be slid into an abutting relationship before shrinking the remainder of the first shrink tube 310.

The first shrink tube 310 may be formed from PTFE. To shrink the first shrink tube 310, a hot box (not shown) may be used to heat the first shrink tube 310 to a temperature in a range about 650° F. to about 800° F. (e.g., about 750° F.) to shrink the first shrink tube 310.

With reference to FIG. 21, after the first shrink tube 310 is shrunk, a tool (e.g., jig 1040) is used to determine that the shrunk length of the first shrink tube 310 (i.e., the first step 302) is within an acceptable range. It will be appreciated that during shrinking of the first shrink tube 310, the length of the first shrink tube 310 may increase. The jig 1040 has a length equal to a desired length of the first step 302 as detailed above. It is contemplated that a first jig may be used having a length equal to a minimum length for the first step 302 and a second jig may be used having a length equal to a maximum length of the first step 302. If the shrunk length of the first shrink tube 310 is less than the minimum length of the first step 302, the coaxial cable 100 is discarded. If the shrunk length of the first shrink tube 310 is greater than the maximum length of the first step 302, the shrunk first shrink tube 310 may be trimmed to a desired length of the first step 302 as detailed above.

Referring now to FIG. 22, with the length of the first step 302 verified to be within the acceptable range, a second shrink tube 320 is slid over the end 144 of the inner conductor 140, over the shrunk first shrink tube 320, and over about 1 inch of the end 134 of the dielectric 130. The second shrink tube 320 has a length of about 4 inches and may be formed from PTFE. With the second shrink tube 320 slid over the about 1 inch of the end 134 of the dielectric 130, the second shrink tube 320 is shrunk over about the 1 inch of the end 134 of the dielectric 130, the shrunk first shrink tube 130 (i.e., the first step 302), and a portion of the inner conductor 140 as shown in FIG. 23. To shrink the second shrink tube 320, a hot box (not shown) may be used to heat the second shrink tube 320 to a temperature in a range about 650° F. to about 800° F. (e.g., about 750° F.). It will be appreciated that the second shrink tube 320 is shrunk from the end of the second shrink tube 320 slid over the dielectric 130 towards the end 144 of the inner conductor 140. After the second shrink tube 320 is shrunk, the second shrink tube 320 is checked to verify that no air bubbles are present within the second shrink tube 320. If air bubbles are present within the second shrink tube 320, the second shrink tube 320 may be reheated to eliminate the air bubbles. If the air bubbles remain after the reheating of the second shrink tube 320, the coaxial cable 100 may be discarded. The portion of the second shrink tube 320 extending distally beyond the first step 302 and over the inner conductor 140 forms the second step 304 of the cable assembly 10 (FIG. 1). It will be appreciated that the second shrink tube 320 seals the abutting connection between the dielectric 130 and the first shrink tube 310 and forms a seal about the inner conductor 140.

After the second step 304 of the cable assembly 10 is formed, critical values may be verified (e.g., the diameter of the braid 120 proximal to the first step 302, the diameter and length of the first step 302, the diameter and the length of the second step 304). Specialized equipment (e.g., a lighted microscope) may be required for accurately measuring critical values of the cable assembly 10.

After the second step 304 of the cable assembly 10 is formed and the critical values are recorded, the braid 120 is tightened from the connection portion 30, over the first and second steps 302, 304, and over the end 144 of the inner conductor 140 to remove any voids between the braid 120 and the dielectric 130, the first step 302, and the second step 304 as shown in FIG. 24. It will be appreciated that as the proximal end of the braid 120 is secured in position about the dielectric 130 by the drawn copper tube 120 as detailed above, tightening the braid 120 may induce tension in the braid 120. In addition, tightening the braid 120 ensures that braid 120 has a minimum thickness over the dielectric 130.

As depicted in FIG. 25 after the braid 120 is tightened over the end 144 of the inner conductor 140, a portion of an end 124 of the braid 120 may be folded over the end 144 of the inner conductor 140 to keep the braid 120 taut. With the braid 120 taut, a tool (e.g., pliers 1010) is used to lightly crimp or tuck the braid 120 around the first step 302 to form a first discrete step down 301, as shown in FIG. 26. Similarly, the braid 120 is tucked around the second step to form a second discrete step down 303 (FIG. 29). Tucking the braid 120 at the first and second step downs 302, 304 keeps tension in the braid 120 and prevents voids from forming between the braid 120 and the dielectric 130, the first step 302, and the second step 304. Preventing voids from forming can assist in maintaining a consistent electrical performance by reducing or eliminating fluid pockets between the braid 120 and the dielectric 130.

Referring now to FIG. 27, the end 124 of the braid 120 is coated a length L₁₁ which can be in a range of about 0.1 inches to about 3 inches or in a range of about 0.2 inches to about 0.6 inches (e.g., about 0.4 inches). As shown, the end 124 of braid 120 is tin-dipped such that the end 144 of the inner conductor 140 is within the coated length L₁₁. The length L₁₁ does not extend to the second step 304. After the length L₁₁ is coated, the end 124 of the braid 120 may be trimmed such that about 0.125 inches of the braid 120 extends past the end 144 of the inner conductor 140.

With reference to FIG. 28, a gap tool (e.g., pliers 1050) is used to set a gap to position a choke tube 330, formed from PTFE, relative to the first step 302. The pliers 1050 have a width equal to a desired gap G for positioning the choke tube 330 about the second step 304 between the second step down 303 and the distal end of the second step 304. To set the desired gap G for the choke tube 330, the pliers 1050 is positioned on the second step 304 with one side abutting the end of the first step 302. With the pliers 1050 positioned on the second step 304, a mark 305 can be made with a marking tool (e.g., a permanent marker) on the braid 120 before releasing the second step 304 from the pliers 1050. The choke tube 330 is then slid over the second end 114 of the radiating portion 20 until an end 332 of the choke tube 330 is positioned at the mark 305 as shown in FIG. 29. When the end 332 of the choke tube 330 is positioned at the mark 305, the choke tube 330 is shrunk over the second step 304 from the mark 305 towards the end 124 of the braid 120.

To shrink the choke tube 330, an initial portion of the choke tube 330 adjacent the mark 305 may be heated in a hot box to about 650° to about 800° (e.g., about 750°). When the initial portion of the choke tube 330 is shrunk, the position of the end 332 of the choke tube 330 is verified to be at the mark 305 before shrinking the remainder of the choke tube 330. If the end 332 of the choke tube 330 is not at the mark 305, the choke tube 330 is slid over the second step 304 to position the end 332 of the choke tube 330 at the mark 305.

Alternatively, instead of marking the second step 304, the end 332 of the choke tube 330 may be slid over the end 124 of the braid 120 with the pliers 1050 positioned on the second step 304 until the end 332 abuts the pliers 1050. With the end 332 abutting the pliers 1050, the choke tube 330 is heated to shrink the choke tube 330 over the second step 304. It will be appreciated that the pliers 1050 will set the desired gap G between the end 332 of the choke tube 330 and the first step 302.

After shrinking of the choke tube 330, the desired gap G may be verified. If the gap G is outside an acceptable range, the coaxial cable 100 is discarded. Specialized equipment (e.g., a lighted microscope) may be required for accurately measuring the gap G.

With reference to FIGS. 30-31, a choke braid 340 is disposed over a portion of the radiating portion 20. The choke braid 340 may be made from the portion 126 of the braid 120 that was discarded above. Alternatively, a piece of coaxial cable may be cut and the outer braid removed to form the choke braid 340. The choke braid 340 can have a length in a range of about 1 inch to about 7 inches or in a range of about 2 inches to about 3 inches (e.g., about 2.5 inches). Referring briefly back to FIGS. 4 and 5, ends of the choke braid 340 are inspected to check if the ends 342, 344 were deformed during cutting to form wings. If a wing was formed during cutting, one or both of the ends of the choke braid 340 are returned to round as detailed above.

With the ends 342, 344 rounded, a tool (e.g., pin 1060) is inserted through the choke braid 340 to open up or enlarge the choke braid 340. The tool may have a diameter of about 0.040 inches. With the pin 1060 disposed within the choke braid 340, a tool (e.g., razor blade 1070) is used to trim end 342 of the choke braid 340 to square and clean the end of 342 of the choke braid 340 as shown in FIG. 30. The pin 1060 may be slid through the choke braid 340 to slightly increase an inner diameter of the choke braid 340 to allow the choke braid 340 to slide over the choke tube 330 as detailed below.

Referring to FIG. 31, the end 342 of the choke braid 340 is slid over the second end 114 of the radiating portion 20 until the end 342 is positioned past the end 332 of the choke tube 330 in a range of about 0.01 inches to about 3 inches (e.g., about 0.15 inches). A portion 346 adjacent the end 342 of the choke braid 340 is then tucked or lightly crimped onto the braid 120 within the gap G between the end 332 of the choke tube 330 and the first step 302. The portion 346 of the choke braid 340 is then soldered to the braid 120, for example with a soldering iron (not shown) and by applying flux and solder to the end 342 of the choke braid 340. The portion 346 of the choke braid 340 is soldered to a portion of the braid 120 disposed within the second step 304. The soldering iron may be a flat tipped soldering iron suitable for soldering the choke braid 340 to the braid 120. During soldering of the portion 346 of the choke braid 340, care is made to prevent the solder from flowing onto the choke tube 330. During soldering of the choke braid 340 to the braid 120, the solder may fill any gaps between the braid 120 and the choke braid 340 as represented by filled gap 348 in FIG. 33.

Continuing to refer to FIG. 29, with the portion 346 of the choke braid 340 soldered in the gap G, the remainder of the choke braid 340 is tightened towards the end 124 of the braid 120 until the choke braid 340 is tight over the choke tube 330. Then, a third shrink tube 350 is slid over the end 124 of the braid 120, the choke braid 340, and a portion of the first step 302 such that an end 352 of the third shrink tube 350 is positioned approximately in the middle of the first step 302 (i.e., the third shrink tube 350 covers about half of the first step 302). With the end 352 of the third shrink tube 350 positioned over a portion of the first step 302 as shown in FIG. 32, the third shrink tube 350 is heated to shrink the third shrink tube 350 onto the braid 120 and the choke braid 340 to form a seal over the solder joint between the choke braid 340 and the braid 120 and to secure the choke braid 340 to the choke tube 330. The third shrink tube 350 may also prevent the solder joint between the choke braid 340 and the braid 120 from flaring. To effect shrinking of the third shrink tube 350, the third shrink tube 350, which is formed from polyethylene terephthalate (PET), is heated to a temperature suitable to begin shrinking the third shrink tube 350.

With reference to FIG. 33, a joint between the choke braid 340 and the braid 120 is sealed with the third shrink tube 350. As shown, the portion 346 of the choke braid 340 is impregnated with solder and is electrically and mechanically coupled to the braid 120. The portion 346 of the choke braid 340 is covered by the third shrink tube 350.

Referring now to FIG. 34, an end 354 of the third shrink tube 350 extends over an end 344 of the choke braid 340. After the third shrink tube 350 is shrunk over the choke braid 340 and choke tube 330, the radiating portion 20 is trimmed. First the inner conductor 140 is trimmed such that the end 144 of the inner conductor 140 is a length L₃₄₀ from the end 344 of the choke braid 340. The length L₃₄₀ can be in a range of about 0.1 inches to about 2 inches (e.g., about 0.63 inches or about 16 mm). As shown, the end 354 of the third shrink tube 350 is in contact with the choke tube 330. The choke tube 330 is trimmed back a length L₃₃₀ from the end 144 of the inner conductor 140 such that a portion of the choke tube 330 is exposed between the end 344 of the choke braid 340 and the braid 120 (i.e., the outer conductor of the ablation catheter assembly 10 (FIG. 1)). The length L₃₃₀ can be in a range of about 0.1 inches to about 2 inches (e.g., about 0.5 inches or about 13 mm). The braid 120 is trimmed a length L₁₂₀ from the end 144 of the inner conductor 140 to expose a portion of the second shrink tube 320. This portion of the braid 120 forms the proximal radiating section 121. The length L₁₂₀ can be in a range of about 0.02 inches to about 2 inches (e.g., about 0.13 inches or about 3.3 mm) As shown, a portion L_(11′) of coated length L₁₁ (FIG. 27) remains over the end of the braid 120. The second shrink tube 320 is trimmed a length L₃₂₀ from the end 144 of the inner conductor 140 to expose the inner conductor 140. The length L₃₂₀ can be in a range of about 0.01 inches to about 1 inch (e.g., about 0.03 inches or about 0.7 mm). The exposed portion of second shrink tube 320 forms a feedgap 321 (FIG. 36) between the proximal radiating section 121 and a distal radiating section 360, described below. The proximal radiating section 121, feedgap 321, and distal radiating section 360 together form a dipole antenna. The choke tube 330 and choke braid 340 together form a choke or balun which is used to control the field of energy which is emitted from the dipole antenna.

The trimming of the lengths as detailed above may form the proximal radiating section 121, the feedgap 321, and the distal radiating section 360 for a particular frequency of electrosurgical energy. As will be appreciated, the lengths of the proximal radiating section 121, the feedgap 321, and the distal radiating section 360 may be proportionally adjusted to accommodate different frequencies of electrosurgical energy.

After the radiating portion 20 is trimmed, as described above, dimensions (e.g., lengths as detailed above and diameters as detailed below) of the radiating portion 20 may be verified. For example, a diameter D₁₄₀ of the inner conductor 140 may be verified to be in a range of about 0.003 inches to 0.2 inches (e.g., about 0.01 inches or about 0.2 mm), a diameter D₃₂₀ of the second shrink tube 320 may be verified to be in a range of about 0.004 inches to about 0.45 inches (e.g., about 0.01 inches or about 0.3 mm), a diameter D₁₂₀ of the braid 120 may be verified to be in a range of about 0.006 inches to about 0.5 inches (e.g., about 0.02 inches or about 0.5 mm, and a diameter D₃₃₀ of the choke tube 330 may be verified to be in a range of about 0.008 inches to about 0.49 inches (e.g., about 0.03 inches or about 0.8 mm).

With reference to FIGS. 35-36, after the radiating portion 20 is trimmed and verified, a distal radiating section 360 is attached to the end 144 of the inner conductor 140. To connect the distal radiating section 360 to the end 144 of the inner conductor 140, the distal radiating section 360 is slid over the end 144 before being soldered to the end 144. As shown, the distal radiating section 360 defines an opening 366 that permits solder to be applied to the distal radiating section 360 and the end 144 of the inner conductor 140. The distal radiating section 360 can include a champher about the opening 366 to prevent damage to the inner conductor 140. In addition, the distal radiating section 360 may include a notch that allows for increased cooling.

With reference to FIG. 37, with the radiating portion 20 completed the connection portion 30 can now be completed as described below. A fourth shrink tube 230 is disposed over the connection between the flared end portion 214 of the rigid tube 210 and the braid 120 at the connection portion 30 to prevent liquid ingress through the rigid tube 210. The fourth shrink tube 230 is slid over the end 212 of the rigid tube 210 with an end 234 of the fourth shrink tube 230 is positioned over the braid 120 about 1 inch past the end portion 214 of the rigid tube 210 with an end 232 of the fourth shrink tube 230 positioned along the rigid tube 210. With the end 234 of the fourth shrink tube 230 positioned over the braid 120, the fourth shrink tube 230 is heated to shrink the fourth shrink tube 230 onto the connection portion 30. To effect shrinking of the fourth shrink tube 230, the fourth shrink tube 230, which is formed from PET, is heated to about 400° F.

Referring to FIG. 38, after the fourth shrink tube 230 is shrunk about the rigid tube 210, the end 212 of the rigid tube 210 is cleaned. It is contemplated that about 0.5 inches of the end 212 of the rigid tube 210 is cleaned with isopropyl alcohol or similar known fluid. It will be appreciated that the wall of the rigid tube 210 is thin such that any abrasive cleaning process can weaken the rigid tube 210. After the end 212 of the rigid tube 210 is cleaned, flux is applied to a portion 213 of the rigid tube 210 adjacent the end 212 before tin dipping the portion 213 into solder for about 5 seconds. After the end 212 of the rigid tube 210 is tin-dipped, any flux residue is cleaned from the end 212. The tin dipping of the end 212 may provide wear resistance for the proximal end 212 of the rigid tube 210 as the rigid tube 210 is engaged by a source of electrosurgical energy 12 (FIG. 1).

With the end 212 of the rigid tube 210 tin-dipped, the tin dipped portion 213 of the rigid tube 210 and the dielectric 130 extending from the end 212 of the rigid tube 210 is stripped to expose the end 142 of the inner conductor 140 as shown in FIG. 39. A razor blade or stripping tool (not shown) may be used to strip the dielectric 130. Then the proximal end 142 of the inner conductor 140 is trimmed to extend from the proximal end 212 of the rigid tube 210 in a range of about 0.01 inches to about 3 inches or in a range of about 0.05 inches to about 0.08 inches (e.g., about 0.06 inches). After the end 142 of the inner conductor 140 is trimmed, the end 142 is sharpened or pointed as shown in FIG. 39.

After the end 142 of the inner conductor 140 is pointed, the cable assembly 10 of FIG. 1 having a liquid sealed rigid or semi-rigid connection portion 30 and a liquid pregnable flexible radiating portion 20 fully assembled from the coaxial cable 100 of FIG. 2. The outer diameter of the completed cable assembly 10 is checked to verify that the outer diameter of the completed cable assembly 10 is below a maximum diameter. If the outer diameter of the completed cable assembly 10 exceeds the maximum outer diameter the completed cable assembly 10 is discarded. The maximum outer diameter of the completed cable assembly 10 may be in a range of about 0.01 inches to about 0.5 inches, 0.02 inches to about 0.4 inches, 0.03 inches to about 0.3 inches, 0.04 inches to about 0.2 inches, 0.05 inches to about 0.1 inches (e.g., about 0.045 inches). The outer diameter of the completed cable assembly 10 is measured by passing dies (not shown) of increasing size over the completed cable assembly 10 until one of the dies passes over the length of the completed cable assembly 10. If a die does not pass over the length of the completed cable assembly 10, the next size die is selected to pass over the completed cable assembly 10. The point at which each die stops (i.e., the outer diameter of the completed cable assembly 10 is larger than the die), may be recorded with other critical values of the cable assembly 10.

Referring to FIGS. 1 and 40-50, layers of the completed cable assembly 10 are shown at different positions along the length of the completed cable assembly 10. As detailed above the completed cable assembly 10 is formed from the coaxial cable 100 (FIG. 2) (i.e., the inner conductor 140, the dielectric 130, and the braid 120), the rigid tube 210, the first shrink tube 310, the second shrink tube 320, the choke tube 330, the choke braid 340, the third shrink tube 350, and the fourth shrink tube 230.

By manufacturing the cable assembly 10 in this manner, the completed cable assembly 10 is capable of maintaining high power output, up to at least 150 W, while being immersed in hypotonic saline and while maintaining a spherical electromagnetic field at a small gauge size, e.g., in a range of about 6 gauge to about 20 gauge. This is accomplished by reducing or eliminating fluid ingress into the seams between dielectric segments to prevent fluid from contacting the inner conductor 140 before the distal radiating section 360, precisely positioning the conductors of the completed cable assembly 10 (e.g., the braid 120, the inner conductor 140, the rigid tube 210, the choke braid 350, the proximal radiating section 121, and the distal radiating section 360), precisely positioning the dielectric segments of the completed cable assembly 10 segments (e.g., the dielectric 130, the first shrink tube 310, the second shrink tube 320, the choke tube 340 and the feedgap 321), and maintaining tight outer dimensions of the completed cable assembly 10 while maintaining the flexibility of the completed cable assembly 10. Further, by permitting fluid to impregnate the braided outer conductor 120, the cable assembly 10 can be cooled more efficiently than cable assemblies 10 having covered or solid outer conductors.

As will be appreciated the completed cable assembly 10 may be enclosed within one or more catheters to permit fluid flow around the cable assembly 10. These catheters may have a columinal configuration, with one catheter nested within another and the cable assembly 10 in the center. Such configuration ensures fluid flow around the cable assembly 10 for cooling and susseptance or near field control purposes as well as other purposes known to those of skill in the art.

While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Any combination of the above embodiments is also envisioned and is within the scope of the appended claims. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope of the claims appended hereto. 

What is claimed:
 1. An ablation cable assembly comprising: a rigid portion disposed at a proximal end portion of the ablation cable assembly and configured to couple to a source of electrosurgical energy and prevent fluid ingress; a flexible central portion extending distally from the rigid portion, the central portion including: an inner conductor; a dielectric disposed about the inner conductor; and a conductive braid disposed about the dielectric and forming an outer-most layer of the central portion, the conductive braid having a proximal portion disposed at the proximal end portion of the ablation cable assembly and directly coupled to a distal portion of the rigid portion, wherein adjacent to a distal end of the rigid portion, the proximal portion of the conductive braid transitions from having a first diameter surrounded by the rigid portion to having a second diameter greater than the first diameter and extending distally from the distal end of the rigid portion; and a radiating portion extending distally from the central portion and configured to deliver electrosurgical energy to tissue.
 2. The ablation cable assembly according to claim 1, wherein the conductive braid is pregnable by fluid.
 3. The ablation cable assembly according to claim 1, wherein the rigid portion and the central portion are configured to deliver at least 150 watts of continuous electrosurgical energy to the radiating portion.
 4. The ablation cable assembly according to claim 1, wherein the entire cable assembly has a diameter of in the range of 0.01 inches to about 0.5 inches.
 5. The ablation cable assembly according to claim 1, wherein the conductive braid is in tension between the rigid portion and the radiating portion.
 6. The ablation cable assembly according to claim 1, wherein the radiating portion includes a first step and a second step.
 7. The ablation cable assembly according to claim 6, wherein the conductive braid extends over the first step and the second step, the conductive braid tucked against the distal end of the dielectric to form a discrete first step down between the dielectric and the first step.
 8. The ablation cable assembly according to claim 6, wherein the conductive braid extends over the first step and the second step, the conductive braid tucked against a distal end of the first step to form a discrete second step down between the first step and the second step.
 9. The ablation cable assembly according to claim 6, wherein the conductive braid extends over the second step, and wherein the radiating portion includes a choke braid disposed about the conductive braid distal of a second step down defined at a proximal end of the second step.
 10. The ablation cable assembly according to claim 9, wherein a proximal portion of the choke braid is in electrical communication with the conductive braid.
 11. The ablation cable assembly according to claim 10, wherein the radiating portion includes a dielectric choke tube disposed between the choke braid and the conductive braid positioned distal of the proximal end of the choke braid.
 12. The ablation cable assembly according to claim 11, wherein the radiating portion includes a third tube disposed about the conductive braid and the choke braid, a proximal portion of the third tube disposed about the first step and a distal portion of the third tube disposed about a portion of the choke tube extending distally from a distal end of the choke braid.
 13. The ablation cable assembly according to claim 1, wherein the dielectric is disposed between the inner conductor and the conductive braid.
 14. The ablation cable assembly according to claim 13, wherein the dielectric is in direct contact with the inner conductor and the conductive braid along an entire length of the central portion.
 15. The ablation cable assembly according to claim 1, wherein the inner conductor forms a first conductive path between the rigid portion and the radiating portion to deliver electrosurgical energy to the radiating portion and the conductive braid forms a second conductive path between the rigid portion and the radiating portion to deliver electrosurgical energy to the radiating portion.
 16. The ablation cable assembly according to claim 15, wherein the rigid portion forms a proximal segment of the second conductive path that is configured to directly couple to a source of electrosurgical energy.
 17. The ablation cable assembly according to claim 1, wherein the inner conductor includes a proximal portion that extends through the rigid portion and a distal portion that extends through the radiating portion.
 18. An ablation cable assembly comprising: a rigid tube disposed at a proximal end portion of the ablation cable assembly and configured to directly couple to a source of electrosurgical energy, the rigid tube having a distal portion; a distal radiating portion configured to deliver electrosurgical energy to tissue; an inner conductor extending through the rigid tube and forming a first conductive path from a proximal end portion of the ablation cable assembly to the distal radiating portion; a dielectric disposed about the inner conductor; and a conductive braid disposed about the dielectric and forming an outer-most layer of the ablation cable assembly between the rigid tube and the distal radiating portion, the conductive braid having a proximal end portion disposed at the proximal end portion of the ablation cable assembly and directly coupled to the distal portion of the rigid tube and a distal end portion disposed within the distal radiating portion to form a second conductive path from the rigid tube to the distal radiating portion, the proximal end portion of the conductive braid transitioning, adjacent to a distal end of the rigid tube, from having a first diameter surrounded by the rigid tube to having a second diameter greater than the first diameter and extending distally from the distal end of the rigid tube.
 19. The ablation cable assembly according to claim 18, wherein the inner conductor has a proximal portion extending proximally from the rigid tube and a distal portion extending through the radiating portion.
 20. An ablation cable assembly, comprising: a rigid tube disposed at a proximal end portion of the ablation cable assembly and configured to couple to a source of electrosurgical energy; an inner conductor; a dielectric surrounding the inner conductor; and a flexible outer conductor surrounding the dielectric and the inner conductor, the flexible outer conductor having a distal portion disposed distal to the rigid tube and a proximal portion surrounded by the rigid tube such that the rigid tube reduces the diameter of the flexible outer conductor at the proximal portion relative to the diameter of the flexible outer conductor at the distal portion. 